Sabot allowing .17-caliber projectile use in a .22-caliber weapon

ABSTRACT

An improved shell, projectile and discarding sabot for converting a .22 caliber weapon for use with a smaller caliber projectile comprising: a rim-fire .22 caliber shell casing holding a quantity of propellant; a discarding sabot inserted into the casing and above the propellant, the discarding sabot being cylindrical in shape; said discarding sabot having internal axially extending cavity for holding a .17 caliber projectile affixed in the cavity of the sabot.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit to provisional application 60/608,171, filed on Sep. 7, 2004, entitled “Sabot Allowing .17-Caliber Projectile Use in a .22-Caliber Weapon,” which is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention is directed to the field of modifying .22 caliber rim-fire ammunition (.22 long rifle and .22 rim-fire [.22 Winchester rim-fire magnum]) to fire .17 caliber projectiles with the use of a .22 caliber discarding sabot.

BACKGROUND OF THE INVENTION

Discarding sabots have long been utilized in weaponry. Simply put, sabots are inserts which enable a gun machined for a particular caliber type of cartridge to accept and fire a smaller caliber projectile. There have been a number of patent directed to the use of discarding sabots for the conversion of projectiles of one caliber so that they may be used in rifles of another caliber. U.S. Pat. No. 4,590,862 discloses a pusher-type discarding sabot for the launching of sub-caliber ballistic projectiles hose dimensions are significantly less than the gun bore diameter from which they are launched, the pusher-type discarding sabot having a pusher plate and bore rider, segmented such that the trajectory imparted upon the pusher plate and bore rider segment is deviant from that of the sub-caliber ballistic projectile upon leaving the gun bore.

U.S. Pat. No. 4,519,317 discloses a sub-caliber projectile having a front end, a tail end and a cylindrical aped mid-section of substantially uniform diameter, sabot means comprising an annular obturating disc member and an annular stabilizing member, first retaining means for releasably securing said members together, said sabot means being mounted on and displaceable along said mid-section between a first position wherein it abuts said front end and a second position adjacent said tail end, and second retaining means for retaining said stabilizing member adjacent said tail end, the arrangement being such that after firing of said projectile said sabot means is displaced from said first position to said second position with the release of said obturating disc member from said stabilizing member and with the retention of the latter on said tail end.

U.S. Pat. No. 6,712,005 is discloses a projectile to be fired from a, gun having a chamber (2) with a conical transition region (4) to a caliber barrel (3) that adjoins the front of the gun. The projectile (5) has a sub-caliber penetrator (6), a jettisonable propelling cage sabot (7) connected to the penetrator (6), and at least one guide band (10) adapted to the caliber barrel (3) secured to the rear side or portion of the sabot. To ensure that the rear region of the propelling cage sabot (7) seals the chamber (2) against propellant gases that are pushing forward, even if the guide band (10) itself is still located in the chamber, an additional sealing ring (14; 17), comprising a deformable plastic, is provided on the existing guide band (10) adapted to the caliber of the barrel (3). The sealing ring assumes the function of providing the initial seal after the cartridge is ignited.

U.S. Pat. No. 6,564,720 discloses a plastic, cup-shaped, multi-petal sabot housing a sub-caliber projectile for use such as in shotgun cartridges. The sabot engages the rifling of the shotgun barrel and transfers the spin to the projectile. A reinforcement disk is advantageously at least partially embedded in a sabot base and has a central aperture and a plurality of additional apertures. Sabot base material extends through the additional apertures. Advantageously, in its relaxed condition, each sabot petal includes a protrusion from its inboard surface for engaging a projectile. The protrusion and its contact area with the projectile are fractions of the local petal width.

U.S. Pat. No. 6,073,560 discloses a sabot for holding a sub-caliber projectile. For use in muzzle loading and other firearms, the sabot includes a plurality of petals which, in one embodiment, encapsulate the projectile. The petals have a high mass portion near the barrel end of the sabot. The portions are subjected to a centrifugal opening force as the sabot exits the firearm barrel upon firing. The centrifugal force causes the petals to clear the flight path of the projectile quickly so that the sabot is less likely to interfere with accurate projectile flight. In one embodiment, the sabot may further include a protective surface for engagement with a ram rod and for protection of the encapsulated projectile, for increased aerodynamic stability.

U.S. Pat. No. 4,000,698 discloses a unique sabot for a sub-caliber or otherwise unusually configured projectile, the sabot being designed to have regions which, under the pressures automatically applied to one or more surfaces of the sabot during the launching of the projectile, fail, causing fracturing of the sabot and separation of the sabot pieces from the projectile within a short distance from the end of the launching device. Particular structure including a frangible sabot body with separation slots shaped to concentrate stresses in the body, and external pressure elements aligned with the slots are provided to achieve the desired end. Immediate break-up of the sabot at the end of the launching means, such as a gun barrel, assures a short area of danger from the sabot fragments in the launching area.

U.S. Pat. No. 5,493,974 discloses a discarding cap that is made up of segments whose bases are secured between a pressure plate and a pressure piece. In order to ensure that all the sabot segments fall away reliably and precisely, the front end of each segment has two surfaces inclined at an angle to each other in the shape of a roof to form a head.

U.S. Pat. No. 6,640,720, to Biserod discloses a translation and locking mechanism for a projectile that is lying in a standby position within a rocket motor in a missile, wherein the projectile is translated with respect to the rocket motor by means of a pyrotechnic charge before the rocket motor is ignited. The rear end of the projectile includes at least one radially spring biased lock and the front part of the rocket motor includes an internal circumferential groove that the at least one lock snaps into when the at least one lock is translated to the groove.

U.S. Pat. No. 4,779,536 directed to increasing the penetration effectiveness, a tip area of the sub-caliber projectile body of a kinetic energy projectile, which immediately follows the possible tip has a greater diameter D over its length L than the diameter d in the following areas of the projectile body.

U.S. Pat. No. 4,756,255 is directed towards a sub-caliber projectile, having a detachable sabot means which comprises leading and trailing obturating members spaced apart along a longitudinal axis of the projectile and releasably secured thereto. A pressure cell is defined between the obturating members communication means being located in the trailing obturating member for effecting communication between the interior of the barrel and the pressure cell and being so designed that the maximum pressure generated in the pressure cell by the influx of propellant gases from the barrel and through the communication means during the launching of the projectile is substantially less than the maximum pressure generated in the barrel and exerted on the trailing obturating member.

U.S. Pat. No. 5,392,714 discloses a sub-calibre projectile of the sabot (pusher-plate) type with discarding cap segments. The projectile has a pressure plate with a rearwards-projecting alignment spike which is inserted into a pressure piece. Held between the pressure plate and the pressure piece are the bases of the cap segments, thus enabling very high gas-pressure forces to be transmitted and the cap segments to be discarded without affecting the target accuracy of the projectile.

While there have been a large number of sabots developed, none have been developed, heretofore, for use with a .22 caliber long rifle or a .22 Winchester rim-fire magnum round. Specifically, it would be desirable to provide a sabot for enabling a .22 caliber weapon to fire a .17 caliber projectile. Seventeen caliber projectiles are very popular for use in so-called varmint guns. A .17 caliber projectile, used with a .22 caliber casing, provides increased range without drop-off.

It is therefore a principal object of the present invention to provide a sabot for use in converting .22 Winchester Magnum Rim-Fire and .22 long rifle rim-fire ammunition for use with smaller caliber projectiles.

This and other objects of the present invention will become apparent from the detailed description which follows.

SUMMARY OF THE INVENTION

In accordance with the present invention a discarding sabot comprising: a cylindrical shaped, multi-petaled member for insertion into a rim-fire cartridge casing for a .22 caliber weapon; said cylindrical shaped member having an internal axial bore to hold a projectile smaller than .22 caliber.

In a further embodiment, the invention is an improved shell, projectile and sabot for converting a .22 caliber weapon for use with a smaller caliber projectile comprising: a rim fire .22 caliber shell casing holding a quantity of propellant; a discarding sabot inserted into casing and above the propellant, the discarding sabot being cylindrical in shape; said sabot having internal axially extending cavity for holding a smaller .17 caliber projectile; and a projectile of .17 caliber affixed in the cavity of the sabot.

In still a further embodiment, the invention is an improved shell, projectile and sabot for converting a .22 caliber weapon for use with a smaller caliber projectile in a rifle or semi-automatic handgun comprising: a rim fire shell .22 caliber casing and holding a quantity of propellant; a discarding sabot inserted into casing and above the propellant, the discarding sabot being cylindrical in shape; said sabot having internal axially extending cavity for holding a .17 caliber projectile; and a projectile of .17 caliber affixed within the cavity of the sabot.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a side perspective view of the present invention in use with a .22 caliber long fire rim-fire brass casing.

FIG. 2 is a side perspective view of the present invention in use with a .22 magnum rim-fire brass casing.

FIG. 3 is an isolated view of the sabot of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is specifically described with reference to the enclosed Figures wherein the same numbers are utilized. In general, the present invention is directed to a sabot system for converting .22 caliber rim-fire ammunition for use with a smaller .17 caliber projectile. A .17 caliber projectile is about one-half the weight of a .22 caliber projectile and has an effective range of two hundred yards.

Specifically, the invention, in a most preferred embodiment, converts a standard .22 Winchester Magnum Rim-Fire (.22 Magnum) and .22 caliber long rifle round from firing a .224 inch diameter projectile to a round capable of firing a 17 caliber projectile. To accomplish this a .224 outside diameter discarding sabot containing a .17 caliber projectile will be inserted into a standard .22 magnum rim-fire and .22 caliber long rifle case containing propellant.

Referring to FIGS. 1 through 3, the invention comprises a .22 caliber case 10, and preferably a rim fire shell casing holding a quantity of propellant. A discarding sabot 13 is inserted in the case and above the propellant. The sabot 13 is cylindrical in shape and fits within the case 10. The sabot 13 has a plurality of expanding petals 15 which open when the sabot leaves the muzzle.

The sabot 13 is preferably constructed from a high density polyethylene plastic which includes a plurality of separated petals that are an extension of its solid high mass base. The sabot 13 has an internal axially extending cavity 14 which hold and support a smaller .17 caliber projectile 16. When the weapon is fired, the projectile 16 and sabot 13 exit the muzzle of the rifle or semi-automatic pistol. The sabot falls away (discards) from the projectile after leaving the muzzle when the petals 15 open.

With the present invention, owners of firearms chambered for the .22 Winchester Magnum Rim-Fire (.22 magnum) round will be able to fire a .17 caliber projectile with no modification to their rifle or semi-automatic pistol. Similarly, owners of firearms chambered for the .22 caliber long rifle rim-fire round will be able to fire a .17 caliber projectile with no modification to their rifle or semi-automatic pistol.

The present invention has been described with reference to the enclosed Figures and above discussed preferred embodiment. The true nature and scope of the invention is to be determined with reference to the claims appended hereto. 

1. A discarding sabot comprising: a cylindrical shaped member for insertion into a cartridge casing for a .22 caliber weapon; said member having an internal axial bore to hold a projectile smaller than .22 caliber.
 2. The discarding sabot of claim 1 wherein the weapon is a semi-automatic .22 caliber handgun chambered for .22 Winchester rim-fire magnum or .22 long rifle ammunition.
 3. The discarding sabot of claim 1 wherein the weapon is a .22 caliber rifle chambered for .22 Winchester rim-fire magnum or .22 long rifle ammunition.
 4. The discarding sabot of claim 1 wherein the projectile is .17 caliber.
 5. An improved shell, projectile and sabot for converting a .22 caliber weapon for use with a smaller caliber projectile comprising: a rim fired .22 caliber shell casing holding a quantity of propellant; a discarding sabot inserted into casing and above the propellant, the discarding sabot being cylindrical in shape; said discarding sabot having internal axially extending cavity for holding a smaller caliber projectile; and a projectile of less than .22 caliber affixed in the cavity of the sabot.
 6. The improved shell, projectile and discarding sabot for converting a .22 caliber weapon for use with a smaller caliber projectile of claim 5 wherein the caliber of the projectile is .17 caliber.
 7. An improved shell, projectile and discarding sabot for converting a .22 caliber weapon for use with a smaller caliber projectile in a rifle or semi-automatic handgun comprising: a rim fire shell .22 caliber casing holding a quantity of propellant; a discarding sabot inserted into casing and above the propellant, the discarding sabot being cylindrical in shape; said discarding sabot having internal axially extending cavity for holding a 17 caliber projectile; and a projectile of .17 caliber affixed within the cavity of the discarding sabot. 